


The secret superpower of one (1) Tony Stark

by childofhebe



Series: MerGenius, MerBillionaire, MerPlayboy, MerPhilanthropist [1]
Category: Captain America - All Media Types, H2O: Just Add Water, Iron Man (Movies), Marvel, Marvel Cinematic Universe, The Avengers (Marvel) - All Media Types
Genre: 3+1 Things, Established Relationship, Fluff, Humor, Language, M/M, Marvel Universe, Mentions of Smut, Merman Tony Stark, POV Steve Rogers, Precious Peter Parker, Romance, Secrets, The Big Reveal at the End, Tony Stark Acting as Peter Parker's Parental Figure, part of a series
Language: English
Status: Completed
Published: 2018-08-27
Updated: 2018-08-27
Packaged: 2019-07-03 11:22:35
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,601
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15817887
Author URL: https://archiveofourown.org/users/childofhebe/pseuds/childofhebe
Summary: Steve noticed Tony's odd behavior some time ago, but he has no idea how to address it. And it worried him a lot because there were just too many layers of it.Then, he finds out why and finds himself very delighted by the reason behind it.Or: Tony Stark gained an unusual superpower he simply can't reveal to anyone.





	The secret superpower of one (1) Tony Stark

**Author's Note:**

> This is my beloved baby.  
> I always wanted to write some crossover like this (search in the Fandoms ;D), and since Yuri on Ice is occupied... Well, I chose MARVEL. And I am so, so glad I did so. This was so worth it and I am extremely excited to explore more of this idea. I have planned so much for this. Series can get started <3
> 
> My wonderful beta: [Maddy](https://archiveofourown.org/users/Madz04)

Steve was very, very worried.

Ever since had Tony come back from the AI related conference in Australia, he acted oddly. It wasn't easy to pinpoint exactly what was wrong, there just wasn't any clear sense to it, but Steve knew. He wasn't sure if he could discuss this with anyone from the team, because the problem included some of the rather personal stuff, and Steve would hate to embarrass Tony. If someone else noticed cracks in Tony's behavior, they haven't brought it up, so Steve couldn't be sure. But he wasn't sure how to bring it up in front of Tony either so… He was just worried.

 

\---

 

Tony loved sex. More importantly, he loved sex with Steve. He loved to subtly hint at it in front of the team (of course never when they had Peter over), until Clint's comments became really gross and Steve couldn't help but blush. Then, Tony patiently waited until they were alone, and then pounced on Steve. When they weren't on a mission, or none important lab work burdened the genius, Tony and Steve were able to repeat this scenario multiple times a day. By now, it was as easy as breathing - Tony held a master degree in arousing his partner, and Steve loved to submit to Tony's powerful siren aura. After all, his boyfriend was one of the sexiest men alive.

 

That's why Tony was the last person that Steve would expect to refuse sex with him. Well, he never did refuse explicitly, but Steve couldn't help but wonder why.

 

For the first time, it happened the day Tony arrived from Australia.

 

“Hey honey,” Steve kissed Tony's cheek as the billionaire slipped straight into his arms after entering the Compound. He was the only member of the ‘Welcome home’ committee because Vision was busy with preparing another culinary catastrophe, Peter was at school and everyone else insisted their paintball training game was too important to pause. Or maybe they just didn't know the exact time Tony would arrive - Steve forgot to tell them. Intentionally. Because he wanted his boyfriend all for himself for a few hours. Who could blame him?

 

When he explained the absence of others to Tony, he just laughed and kissed Steve. “You're the worst, two weeks without me and you're thirstier than a koala. We should probably take an advantage of your naughtiness to the fullest, what do you think, Captain?”

 

“I say yes, we should,” Steve smirked and tugged Tony's hand. World's two most powerful superheroes ran away to their bedroom like a pair of giggling teenagers and left Happy to cringe in the doorway and deal with luggage on his own.

 

“So, what do you say we begin with a shower to freshen you up after the flight?” Steve murmured in between kisses as he locked their door behind them. Tony hummed, and Steve took it as a yes, so he nudged Tony in the direction of their bathroom. To his surprise, Tony stood his ground and instead moved to the bed.

“I already took shower in the jet, don't worry about it,” Tony crawled into the bed and slipped out of his jacket, throwing it on the ground. Steve noticed that Tony wore more casual clothes than he usually did while traveling, so it was probably true. And yet, he hesitated and took his shirt off with twisted eyebrows.

 

“Steve Grant Rogers, you have a lover with uncomfortably tight pants on your bed, and you hesitate. Does that tent I can see from here make you barbaric? I can think of multiple ways how to avail that better.”

 

Steve smirked, shrugged the feeling off and joined his impatient lover. Maybe it was nothing.

 

But it clearly was something, because it happened again the tomorrow evening.

 

Tony sat comfortably on the bed, working on the StarkPad when Steve entered their bedroom. Steve was very happy with the fact that Tony's sleep schedule improved when they got together. It wasn't perfect, but most of the nights they were able to go to sleep together at the same time.

 

“I am coming straight from the gym because I thought my beautiful boyfriend would like to join me in the shower. What do you think?”

 

Tony didn't even look up from the StarkPad. “Umm, no thanks dear, I'd pass. I really need to finish these graphs for Pepper before we go to sleep.”

 

This shocked Steve. Tony never before preferred work from Pepper over the sex invitation. Steve was the one to force Tony to work instead of sex multiple times because if Captain America was afraid of something, it was angry Pepper Potts.

 

“Close your mouth, or the fly would die there and if that happens, I'm not kissing you.”

 

Steve found himself nodding and walking for the shower alone. He was probably too shocked to argue.

 

But then, it happened again, and again, and again. As if Tony suddenly turned on his workaholic mode - all of his assignments were on time without the need of Steve's or Rhodey's or Pepper's scolding. And Steve went two months without the shower sex.

 

He had no idea how to address the issue - Tony never denied all other sorts of sex. In their bed, kitchen, workshop, they even banged in a gym couple times during those two months. He had seen his boyfriend naked almost every day - but never in the shower. Was it even an issue? Maybe it was unintentional, and Steve was just imagining bigger meanings. If there weren't for other things, he would almost let it go.

 

\---

 

Steve often found Tony in weird situations even before Australia.

Tony sitting asleep on a kitchen stool, because he couldn't make it until his morning coffee brewed? Normal. Especially after the long night in the workshop.

Tony with his arms around Peter's waist, with his Iron Man gloves on more often than not, pulling Spider-Boy from the wall? Usual. Peter's newest web fluid was incredibly durable, and when he forgot some on his palms, he was doomed to be stuck.

Tony, yelling, buried under metal junk and sprinkled with the fire extinguisher, while Dum-E and U whirred around and panicked? Not that usual, but it happened often enough for Steve not to panic and resolve the situation with the cold head.

 

But in the last two months, the number and weirdness of these situations escalated through the roof of Steve's sanity.

 

It didn't help that in 9 occasions out of 10 they involved one friendly neighborhood Peter Parker.

 

When he was at the Compound, Peter was inseparable from Tony. The rest of the team thought it was adorable, how the two functioned together. They worked in the workshop, watched movies, talked, argued, prepared food, developed a ton of inside jokes, and generally radiated the “Father and Son” aura. Peter had always adored Tony, even from the times before his own superhero ambitions, and Tony… simply loved Peter. There was no other way to say it. It was hilarious and cute and damn, fatherhood looked really good on Tony.

 

But now, Steve couldn't help but notice the desperation hiding behind their closeness.

 

Like the time Tony prepared the morning coffee and in his sleepy clumsiness poured water over the counter and his hands. Out of nowhere, Peter appeared in the kitchen, caused Steve to almost jump out of his skin (Exactly for how long was Peter hiding somewhere around? Holy shit, they just made out on the counter!), only to hand Tony the towel and disappear again.

 

“What was that about?” Steve asked, confused, but got no answer.

 

Or the times when Peter got a cough or a sensory overload, so he couldn't go to the training or some team bonding activity, and Tony stayed with him in the workshop or his room as the right mother hen.

 

“Oh come on, Spider-Baby, afraid of the storm? Thor would be scandalized! Paintball in the real woods and rain, there's nothing better!” Clint teased Peter once. The teen was curled up in Tony's lap and a blanket, slightly trembling in the warm living room.

“Get out already, douchebag, don't you see he's ill?” Tony barked, not tearing his eyes from the TV with The Alien on, and Clint scoffed. “You sure your little puppy won't melt from your bad language?” Clint took his paintball gun and waved at the Captain. “C'mon Cap, Tin Man can suck a sugar cane. I'm on the team with you!” and with that, he pulled Steve out into the rain.

 

“You sure, Tones? I think he looks fine, plus water could help him with the overload.” Rhodey seemed genuinely worried, but also a little fed up with his best friend's stubbornness.

“It might help, but certainly not when our favorite jet Mr. Barton wants to play water polo. Besides, Spider-Baby doesn't know how to swim, and I don't want to teach him with the possibility of Wilson and Barton drowning him for fun the second I turn away. Have fun and make sure F.R.I.D.A.Y. records the best moments,” Tony said and closed Peter's door into Rhodey's face. Rhodey turned on Steve and sighed. “I guess this means Tony won't be joining us either, and that means that I don't have to put out with Sam and Clint teasing my swim trunks. We need another referee than Vision, or by the dinner, no one would be talking to anyone again.”

 

But the strangest thing happened the second week after Tony's arrival from Australia. Bruce happened to come back two days ago, and he immediately went along really great with Peter. They hang out together in Bruce's lab majority of the time, Peter's well of questions for his favorite scientist never drying.

 

“Peter? Are you alright? What are you doing there?” Steve asked and knocked on the locked door, concerned when he heard Peter's voice from Bruce's chemical lab. He didn't hear Bruce, so he thought Peter was talking to F.R.I.D.A.Y. or his own AI. Peter usually made his web-fluid in Tony's workshop, because it wasn't that difficult and he liked the company. A thought of a teenager locked in the fully advanced chemical lab wasn't pretty, no matter how smart the teen was.

 

“Uh! Nothing! I am...just…” Peter's voice ranged out, only to be interrupted by another voice. “We were having an...um…” Bruce. Steve frowned and tried the door again.

“Pop quiz!” Peter filled in again. Steve frowned further.

“And why are the door locked and windows covered?”

“That's my fault!” the third voice joined, and Steve was shocked to recognize Tony. What the hell were they up to?

“Well, you should come out. Vision said the dinner is ready, and I haven't seen any of you all day long. Now I know where you were, but I still have no idea why.”

 

A jumble of sounds came out of the lab - shuffling, whispering, even a strangely familiar clicking sound. Then, the door opened to reveal Peter with a suspiciously wide smile. There was a hint of panic in his eyes, that Steve immediately picked up on.

“Food sounds very good, Cap!” he saluted and tried to push through Steve, but the super soldier wasn't buying it. Steve pushed Peter back into the lab instead and then entered himself.

 

Bruce was sitting behind the table in his lab coat and glasses, and his smile was twitching. Steve didn't know if it was because of laughter or nervosity, but he really hoped for the former. The tables from the middle of the room were gone, pushed against the wall, and in the freed space there was an Iron Man themed kiddie pool full of water. However, water was poured all over the floor in generous puddles, and Bruce's and Peter's clothes were also wet. But the weirdest thing was hanging from the ceiling straight above the kiddie pool - Tony. Upside down, with a huge thick web cocoon wrapped around his body.

 

“What the hell happened here?” Steve breathed out, ignoring Tony's murmur of: “Language.” and turning on Peter. Spider kid looked at him back with his wide doe panicked eyes, clearly unable to answer.

 

“Calm down, I just...lost a bet.” Tony casually said, slightly wriggling in his cocoon. Steve felt close to a breakdown.

“What?! Which bet? Who proposed this as a punishment for the loser? How long are you like this?”

Tony groaned, interrupting Steve's flood of questions. “I would rather not dive into it, Stevey. My head hurts and my pride is a little bit in pieces right now.”

 

Steve quickly turned back on Peter. “Get him out of that thing!” Peter, still looking panicked, nodded and scrambled to the table. He almost slipped on a water puddle, and then retrieved a big spray bottle marked 'WEB DISSOLVER'.

 

Steve pulled the kiddie pool from under Tony, and Peter climbed on the ceiling. “I hope you'll catch me, Prince Charming,” Tony said and Steve smirked, pressing a kiss on Tony's forehead (they were in the exact same height now).

Peter removed Tony from the ceiling, and Steve swiftly caught his boyfriend in his arms. Peter jumped down and sprayed the dissolver around Tony's body, slowly tearing the webbing from him with the free hand. Steve still felt the uneasiness, how worried Peter and Bruce seemed. Why though? They shouldn't web Tony upside down on the ceiling if they were worried for him. Wasn't Tony heavier than usual though? And were his legs always this long? Or was all just because of the web?

 

The web was letting out generous amounts of steam as it dissolved, and Steve looked at Peter. “I hope this smoke isn't poisonous Peter,” Steve said, trying to break the thick silence.

“Oof, of course not, Cap! It doesn't usually smoke this much, but since this is a lot of webbing, I suppose it is because of it… But we are safe, as safe as we can ever be!” Peter let out a flood of the ramble.

“Yup, no hurry, Underoos. We won't miss much if Vision was the one in charge of food today,” Tony said, his voice slightly choked.

“Actually, Wanda was. Vision only helped,” Steve cleared, a smile creeping on his lips. Tony nodded and turned his head to Peter. “Dissolve the fastest you can, before Clint and Sam eat everything again.”

 

It was strange, but as Peter tore another piece of the steaming web from Tony and a glimpse of the black shirt appeared, he visibly relaxed. So did Bruce, and Tony let out a sigh of relief. And when Tony was fully free, except few pieces here and there that stuck on his clothes, he refused to be let down on the wet ground.

“Nah-ah, Prince Charming. Bring your princess to our chambers so I can change clothes and then wine and dine with our moron friends. And if anyone speaks of this, I would have all of your automatic clearances deleted and you would have to remember a separate code for every room in this Compound.”

 

\---

 

Some Avengers didn't usually hang out at the Compound. They had a family, other business to attend to, or simply didn't have the taste for it.

One of them was Doctor Stephen Strange, the powerful wiz-ehrm, the powerful Master of the Mystic Arts. When he appeared at the Compound, it was often because he made some important discovery in his books, or wanted a piece of Wanda's sponge cake (he always knew when she made one). The one thing was sure - Stephen and Tony hated each other's guts. Steve wasn't sure if it was because Tony and Stephen were so similar, or if… No, it was definitely that.

 

Three days from Tony's arrival from Australia, Strange walked into their living room in the middle of the movie night, and with his eyes fixed on Tony, he scoffed: “So, it's true.”

It was mostly dark in the room, with only the TV screen radiating the light, but Steve could pick up at how Tony's face paled. He stood up, facing Strange, successfully ignoring the curious glances of others. A little smile appeared on Strange's face and then he chuckled.

“Of all people… Even in my wildest visions I never would've imagined that karma would catch the King of Douchebags like this, you finally got what you deserved Stark, this is so hilarious,” and then he was laughing, and Tony was springing forward, grabbing Strange's shoulder and pulling him from the living room.

Rhodey was the first to say something. “You know what that was about?” Everybody shook their heads, and Steve was worried.

Strange had left after that, and when Steve asked Tony about it later, he just dismissed the question like: “Something magical went off in his head and he assumed things. Asshole.”

 

But that didn't change the fact that Strange started to come to the Compound much more often after this incident. In fact, when Peter wasn't around, it was more likely that Steve would find Tony in the company of the Stephen than not. He didn't like it in the slightest.

 

He walked into the workshop the other day and was greeted by an adorable sight - Dum-E and U playing a catch with the Cloak of Levitation, and Tony watching how Strange pulled water from the multiple buckets with his magic and created various patterns with it in the air. The weird thing was - Strange sat on the couch with his hands in his lap, while Tony's hands were outstretched as if he wanted to touch the floating blobs of water.

Steve coughed, and the scenery broke. Dum-E, U, and Cloak froze, Tony violently jerked and Strange let go of his magic and all of the water poured down on the floor. Strange turned on Steve and completely seriously said: “We have a magic lesson here.”

Tony, suddenly strangely curled up on his chair, nodded. “Yeah… Lesson… I guess.”

 

Another day he found them in the kitchen. Tony, Strange, Bruce and Peter were all sitting around a huge bowl of ice cream (actually there were various flavors of ice cream, sliced bananas and pineapples, strawberries, cherries, chocolate syrup and whipped cream), the spoons in their hands - except Tony, who had his hands outstretched around the bowl.

Peter dipped his spoon into the chocolate section (maybe even chocolate coconut, little spider's favorite), and took the spoon out full of ice cream into his mouth. “Maybe a little colder.”

A moment later (Steve would've sworn he had seen the whipped cream thickening at express speed right in front of his eyes) Bruce was the one to check out the vanilla section. “Now it is too cold, my brain is freezing,” scientist complained. Strange rolled his eyes and Tony groaned. Then, the whipped cream unfroze again (and Steve still couldn't believe that he was able to actually see it).

“Come on, settle already, I don't want my beloved coffee one ruined,” Tony mumbled, and Strange was the next to dip his spoon into the green section (a mint probably?). “Just an hour ago you whined to me about training. They are doing you a favor,” he shrugged and licked the spoon clean. “Little colder.”

Tony's head crashed on the table, and the whipped cream once again thickened.

Steve turned around and left, confused beyond his lines. Strange could do what he wanted, and if he wanted to use his powers for changing the temperature of ice cream, he could. It was maybe a little odd, but incredibly useful.

 

Strange often used his magic in general, as Steve noticed after few of his now frequent visits. He teleported a lot, levitated around, created portals to get things from other rooms and brought things to himself with his magic. Steve had always known that the Strange was present when the flying book hit him in any random corridor.

“It's not like I don't like him, especially around you, but I can't help but wonder why is he suddenly all over the Compound and especially all over…” Steve couldn't hold it in one evening when he and Tony were taking some midnight snacks before going to sleep. For Steve that meant a glass of water, for Tony a glass of wine. It used to be scotch, but hey - progress is progress.

“...All over me?” Tony smiled as he sipped the wine, and Steve abruptly stopped, a little scandalized by his boyfriend's amusement.

“I'm not jealous.”

“Oh, you are. You are so jealous I can see the steam pouring out of your ears. But you work yourself up over nothing - there is nothing between me and Strange besides old, good, healthy burning hatred. And a respect. Solely from his side. Obviously.”

It was Steve's turn to smile. “Obviously.” He lifted his glass of water to take a sip.

A second later, the book flew out from behind the corner, collided with Steve's hand, and sent the glass of water flying right into Tony's chest.

Glass didn't break, which was a miracle, but all of the water poured over Tony's face and shirt. The glass clattered on the ground, and Tony looked up, his eyes as wide as the antelope in headlights. Steve quickly reached for him, not comprehending Tony's utter panic that radiated off him in waves.

“Whoa, I'm so…” Steve didn't get to finish, because Tony turned and sprinted away, as fast as if his life depended on it. Steve, to his surprise, didn't run after him right away.

“Wh… What? Tony? What happened? Wait!”

Tony sprinted into the closest door, pulled it open, slipped inside and shut them. When Steve got to the door and pulled at the handle, they were locked. “Tony! Tony, open up! What happened? Did I do something? I am really sorry, honey, please open up,” Steve gently knocked on the door at first, but then he heard a loud bang from inside and his knocking merged into banging. “Tony! Did you just fall? Are you hurt? Open the damn door!”

 

“Why are you making such a noise?” a calm voice ranged in his ears and he sharply turned to face Stephen Strange. Steve tried to collect himself, and he even said: “Well, Tony… and I was…”

“Perfect example of the coursebook answer, Captain. It seems I should take care of it myself,” and with those words, he closed his eyes and what seemed like his ghost flew out of his body, now help upward only by the Cloak. The ghost came through the door absolutely effortlessly, and the next thing Steve heard was Tony's: “Are you fucking kidding me?!”

“Captain Rogers seems rather restless because of your dramatic actions. You should hurry before he tears down the door,” he heard Strange, muffled by the door, but still clear as a day as if it wasn't just a ghost.

“I am!” Tony snarled. Then, an odd hissing sound came, and Steve would've sworn the steam came from under the door.

Tony unlocked the door and came out, unharmed, slightly disheveled and with the neutral look on his face. Steve immediately grabbed at his hand. “God, Tony, are you alright? What happened?”

Tony looked him in the eye and stuttered: “I...panicked?”

“You are telling me that or asking me that?”

“Don't pull an elementary school teacher quotes on me, I consider that a dick move. I panicked. I am telling you that. Let's just… Go to bed. Alright? Please?”

Steve wasn't sure if Tony learned those puppy eyes from Peter, or if he always had them in him and just yet didn't find anyone who would submit to them. Well, there was. He gently kissed Tony's cheek, not caring in the slightest that Strange watched them, not from his own body again, with a judging look on his face. “Of course, love.”

 

\---

 

As the majority of the issues in their little Avengers household does, this problem also got sorted out on the battlefield.

 

Hydro-man appeared on the shores of the Long Island Sound, and in the gigantic man-made-of-seawater form walked around the beaches. He destroyed a big amount of woods, some villages, some summer camp, and now he was terrorizing Montauk.

 

They have been doing everything they could - but how do you fight a man-shaped tsunami? Steve himself wasn't very useful, all he could do was to throw rocks and help occasional civillians. Clint with his explosive arrows did some damage, but explosions simply weren't strong enough to affect Hydro-man for long. The same problem was with Natasha's widow bites - effective, but weak against the mass of water. Sam's wings and weapons also weren't much of a use. Bruce stayed at the compound - they all decided that Hydro-man did enough damage even without Hulk joining the rodeo.

The most effective were Vision with his strong mind stone beams, Wanda with her magic, and Tony and Rhodey with their energy blasts. Unfortunately, Wanda was swept away by the crumpled tree trunk that flew out of Hydro-man's arm, and Vision immediately flew to retrieve her, leaving them both behind.

Peter tried to use his sticky abilities, borrowed a surf from one beach hut and _somehow surfed_ all the way up the monster's back. Stopping on the spacious shoulder, he balanced himself there and then told everyone into the comms: “Does anyone think that a web grenade would do any damage here?”

“I doubt so, Underoos,” Tony panted. Steve has been watching his boyfriend for a while - instead of choosing a steady position and only making a move when dodging the big water arms (like Rhodey did), Tony was constantly moving, shooting unexpectedly, and expertly dodging every drop of water. Steve didn't know why he did it - all of them were completely soaked wet by now, even Vision. But Iron Man’s armor had next to none water on its surface. The constant movement clearly exhausted Tony, and now, when they were stripped of their successful members, he had to multiply his efforts.

“Would anyone lend me the real grenade?”

“NO!” the collective answer rang through comms, and Peter huffed. “Where's Deadpool when the spider needs him.”

“Peter Benjamin Parker, if I hear you say that name once again, I'll take the suit and launch you into the atmosphere in Veronica, and you'll be grounded there until…”

“Peter WATCH OUT!” Steve yelled, interrupting Tony. The young spider was already in the air, his spidey senses working, but they didn't help this time. Hydro-man grew another monstrous hand from his back to sweep Peter from his shoulder. Peter couldn't dodge entirely, and the mass of water hit him hard and sent him flying towards the sea. There was a silence in the comms, as everyone else, including Tony, stopped and watched him fall as fast as the stone. Then, quiet words echoed in comms: “Guys… I can't swim.”

Peter hit the sea surface with an enormous splash but didn't come above.

 

A chaos erupted. Clint shot about a dozen arrows at once into Hydro-man's legs, making him stumble as his legs fell apart for a minute. Natasha then hopped up into a piece of tree trunk sticking out of Hydro-man's hip and pushed both of her electric batons into him. His whole posture shifted, and Steve was pretty sure that if it could, it would roar.

Tony did a swift turn in the air and flew after Peter. Without hesitation, he breached the water surface, and it closed above the Iron Man suit.

As if called, Vision came back with unconscious Wanda in arms. “I believe I can leave her with you, Captain,” the android handed Scarlet Witch to Steve, who just nodded. It wasn't like he could do much in this battle, so he could at least treat the cut on Wanda's head. Besides, something like anger could be heard in Vision's voice, and Steve didn't want to miss the outcome of that. He quickly brought Wanda on the beach near the big stony reef, laid her down to the sand, and began to treat her wound.

Tony breached the surface moments later, with an unmoving Peter in his arms, and without a single word set him into the sand near Steve and Wanda. Then, he turned and set off back into the sky, in a strangely smooth motion. Steve frowned, was Tony really that mad at Peter for talking about Wade Wilson? That was odd. Another thing on his endless list.

 

Steve pulled Peter's mask from his face and teen immediately woke up, flipped on his stomach like a dead fish and coughed up a whole bucket of water. Steve smiled, patted his back reassuringly and then went back to Wanda.

He didn't really pay attention to the loud splashes near him, he was on a beach after all, and with Vision back in the game, Hydro-man let go of some water mass and shrunk a little (probably so he could dodge better).

Then, Tony talked. And Steve stopped dead in his tracks, shocked.

“Spider-Baby's fine, let's destroy this motherfucker and go home, I want my five o'clock coffee.”

“It's half past three, Tony,” Rhodey pointed out, sounding absolutely normal through the comms.

“I sometimes cheat,” Tony admitted, and Steve heard it again.

 

You know how it sounds when you phone with someone in the same house? You hear them from the phone through one ear, and faintly hear their real voice through another ear. It is confusing, and it often forces you to shut the door so you can hear just one of those sounds.

So, that's exactly what Steve did. He took out an earpiece and listened to his favorite voice on the world, that was still echoing from behind the stone reef.

“Rhodey, Vis, let's try and cut off douchebag's head. It would maybe just piss him off, but I kind of want to piss him off,” it was definitely Tony. But how? Well, Steve, of course, knows that Tony's suits can be remotely controlled by headsets and glasses, but why would Tony not be in the suit right now? Had he injured himself? If that's the case, why didn't he say something, or alert them? Since when he is hiding here? So many questions, so little answers.

 

Steve quietly climbed the reef and peeked over the highest rock on the other side. There was a little lagoon, surrounded by jagged rocks of a reef, with one opening leading into the sea on the other side. The reef around the lagoon wasn't very high, but it did a good job at hiding its contents A few small fishes swam lazily in the clear lagoon, and one big, colorful fish…

 

Wait a second. No, Steve surely wasn't seeing what he just saw.

 

It was Tony. Anthony Edward Stark, Iron Man, genius, billionaire, playboy, philanthropist, and Steve's boyfriend, not necessarily in this order. He laid leaned against the reef, his head down, one hand enclosed on the telepresence glasses. Steve couldn't see Tony's face, and he probably had an expression of a deep focus, as he was controlling the suit in full fight. But, what he could see underneath Tony took Steve's breath away.

 

Instead of legs, Tony had a tail. A beautiful, lean and sleek tail, slightly longer than Tony's legs, ending in big, sharp-ended double fin. The colors of the tail were marvelous - rather matt velvet red scales were mixed with shiny golden and bronze scales, and together they created the gorgeous collage of colors and light. The weak tide in the lagoon slowly rocked the fin, and with the movement, it almost looked like scales were shifting between those colors in an endless optical play. Tony was sitting on the heightened rock, leaving only half of the tail dipped in water.

 

Steve moved his leg to stand up, confused beyond anything. He seriously needed to take a breath. His enhanced metabolism, in fact, disabled any basic drugs from taking effect on him, so everything he had just seen was true, not just a hallucination or a dream. This was something he couldn't imagine even in the wildest dreams! He needed to take a break, climb down, check on Peter and Wanda, and maybe then climb back and check if it really isn't some sort of delusion.

His plans were shattered next second, as the little stone freed up from under his leg, rolled towards the edge and fell with a quiet splash into the lagoon. Steve sighed with defeat and leaned back down to look at Tony, who was now staring up with absolute terror written on his face.

 

Having a mermaid tail didn't have the slightest effect on Tony's face. His hair was sopping wet, strands sticking everywhere instead of the neat styled look it usually had, but his goatee, his flawless skin, and his warm brown eyes were all the same. The silence between them prolonged, Steve hiding his inner storm behind the mask of neutral awe, and Tony's terror visibly growing with every passing second, even though he tried very hard to sustain it. He took off the glasses with his left hand, and Steve noted how the hand shook. That wasn't good, Steve didn't want to get Tony this miserable. He needed to calm the situation down.

 

“Tony,” he breathed out, forcing his voice to remain calm. Tony's features immediately hardened, as if he was pulled into reality with Steve's voice, and reminded that there was no imminent danger, certainly not from Steve.

“Hey, dear. Got bored at the party?” and here it was, Tony hiding behind an impenetrable wall of verbal sparring. Steve suppressed a sigh and shuffled closer, sitting on the edge of reef above Tony. There was no reaction on that from Tony, he remained absolutely tense. That was good, somehow, Steve supposed.

“Tony… I don't know what to say,” he admitted after a while and shrugged. “Can I come down to you?”

Tony gave a curt nod, and Steve quickly jumped down, as if afraid that Tony would change his mind.

He landed on the stone floor, water splashing around. He was mid-thigh deep in it, and as he came closer to his boyfriend, he noticed their height difference - only a few inches bigger than it usually was. His eyes scanned Tony once again, picking on the light reflected in Tony's tail, and the way his skin seemed to be unusually glowing and ethereal. He couldn't help it. “You're… You're beautiful Tony.”

Brown eyes softened a tiny bit, and Steve knew that he probably didn't mess this up. Yet.

“Thanks, I guess,” he murmured, Steve came one more step closer. He was now at arm's reach from the tail, but he didn't want to do anything to startle Tony, so he kept his hands firmly at his sides.

“You can touch it,” he heard Tony blurt out, and it made him smile. Of course Tony would know exactly what he was thinking. So he outreached a hand and gently touched the tail, where Tony's mid-thigh would normally be. The scales were incredibly silky and delicate, and Steve's breath hitched again. Tony let out a quiet huff too, probably because of how cold the tail felt to the touch (and Steve's hands were as warm as ever).

 

“Tony… How?” Steve brought his eyes up from the gorgeous color and light play under his hands to find his favorite pair of eyes. Tony let out a frustrated groan at the question.

“Oh, well, I just fell into a sparkly lake and let me tell you, I would definitely recommend. Best decision of my life, absolutely not regretting this…” Tony abruptly stopped when he picked up on Steve's confused face. A long, worn out sigh escaped him, and he curled onto himself, burying his face in palms.

“What do you want to know? It's as simple as this. I touch water, ten seconds, and then boom, I grow a fucking mermaid tail. It's apparently some kind of freaking irreversible moon magic - or Strange is just messing with me, I have no idea,” Tony rarely sounded defeated, but now he did, and Steve's shoulders slumped at that. Tony hated when he couldn't understand something, and this seemed like a solid case of an unexplainable event.

“So… It happened in Australia?” Steve asked, just to confirm his theory. Tony gave him a nod, avoiding eye contact. “And… Who else knows?”

“Strange somehow found out on his own. He explained it as some movements in the magical field around the Compound, so he researched and found out. Then, I told Bruce… I had to, I was going crazy from the scientific absurdity of this thing. And Peter… Found out on an accident. Found me like this once. Funny story. I'll tell you someday. But I really could use him - he is the only one from the gang able to lift me, except maybe you. This thing…” he moved with the tail, and fin splashed, “...is incredibly heavy.”

“So… No one else? How did you manage to keep this from everyone?”

Tony gave him a grim look, and Steve recollected. “Peter, right?”

“Of course. He is incredible. Watches me better than F.R.I.D.A.Y. does. I could go for days without any drop on my skin thanks to him. And it somehow doesn't apply on sweat, otherwise everyone would know by now,” Tony said and shifted, possibly growing uncomfortable under Steve's stare.

“That's…” Steve began, but Tony cut him off.

“I know it's crazy, and I would never have thought that this could happen to anyone, let alone me, but I know how to live with it by now. Not how to control it, I don't even know if that is possible, and I am slowly learning to manage the powers that came with this enormous piece of salmon attached to my body, so I figured it would be better not to tell you. I know you're mad, I mean, this is a pretty big deal, but…”

Steve couldn't listen to it anymore. He made three fast steps, water splashing around, and he leaned in to kiss his genius, but still silly boyfriend. His fingers gently touched his chin to keep him still, and was delighted to notice how the tension escaped from Tony's body upon the kiss. It was gentle, and Tony's lips and skin were possibly even silkier than usually. Tony's hands hugged his shoulders, not letting them part after they ended the kiss.

 

Steve smiled gently and caressed Tony's cheek. “They say that when you kiss a mermaid, you'll be able to breathe underwater.”

“Booh. Pirates of the Caribbean 4,” Tony lifted an eyebrow, but he couldn't hide his smile.

“So what? Maybe it is true,” Steve said, his caressing hand now moving to Tony's chest, belly, and the base of the tail.

“It's not, even I can't breathe underwater, why would my kiss give you that ability?” Tony was now smirking. Steve blinked, confused.

“You can't?”

“No, but I can hold my breath for pretty long. Tested it with Peter and Bruce in the pool. Last time I endured two hours. I can swim very fast - though we never had enough space to measure exactly how fast. Bruce wanted to suggest an Avengers vacation in Montauk to disguise it and test it out on the open ocean, but, well… I guess Montauk is in pieces now.”

The excited science sparkle was back in Tony's eyes as he talked about this, and that lifted Steve's spirits again. “And what about those powers you were talking about?”

 

Before Tony was able to answer, a loud crash interrupted them. Tony scrambled to put glasses back on his face and then cursed. “Watery son of a bitch,” he looked seriously at Steve. “He sent Sam into Clint's explosive arrow. Bit of a mess. F.R.I.D.A.Y., how much power do we have left?”

Steve chewed at his lip. It worried him for a while, but they really had no idea as for how to defeat Hydro-man. They defeated an alien army, but couldn't do this?

“My powers… I can move water, boil it, freeze…” Tony muttered, clearly focusing on his glasses for now, but then abruptly stopped. “Holy shit,” he cursed, looking Steve in the eye. “You think you can lift me so I can see over the reef, Prince Charming?”

Steve nodded, confused at the question. “Sure, it's not that high, but wh…”

“You'll see. Quick.”

So Steve did, he lifted Tony bridal style and found something reminding of stairs on the ragged reef, and then he laid Tony down. Merman rolled on his stomach and supported himself with his elbows. “Here we go,” he muttered and lifted both of his hands, palms pointing at the water monster. “F.R.I.D.A.Y., retreat and charge it up. On my signal, I want the strongest beam we have on stock.”

 

Then, Tony put on the face of deep concentration, and Steve was almost afraid to touch him. The light emitted from his skin wavered a bit, the air around suddenly vibrated. The hair on the back of Steve's head stood up, and temperature around suddenly dropped.

It was there again - the unnatural feeling of quickened time. And then, Hydro-man's big legs, set into the ground about 300 meters from them, started to freeze.

Slowly, but securely, the white ice covered the surface of monster's legs, lower abdomen, and the belly. The monster stopped dead in its tracks, looking down, the confusion written into the blank face. It started to hit still thin ice layer, but it froze again immediately after it cracked. Avengers around followed Iron Man's armor example and quickly retreated, exchanging confused looks - no one knew where this came from.

It took another while, but ice covered Hydro-man's arms too, and then his head. He stopped every movement, and then all Steve could hear was the loud cracking of the growing ice inside him, as the monster froze through and through.

 

Tony beneath him started to shiver. The light from his skin was almost gone, and he struggled to keep himself upright. He mumbled something incoherent, and Steve gently caught his hands, as they were about to crash down. “You can do it,” he whispered gently into Tony's ear. “Only a little while.”

He didn't even know what he was cheering on, but it clearly worked. Tony took a deep breath and wrinkles of concentration on his face deepened.

Just as the single drop of blood escaped Tony's nose and splashed against the rock under, he yelled: “F.R.I.D.A.Y., now!” and let his hands fall completely. The Iron Man armor high above them lined up its hands and fired the powerful blast from both hand repulsors and the chest reactor, straight into the chest of the frozen monster. Ice exploded, big pieces of it flying into the air, landing back in the ocean, or on the ground, where they shattered even more. Avengers scrambled to find a shelter, but if Steve was correct, no one got hurt - possibly thanks to Tony, who had his hands in the air again, but with different gesture this time - his hand kind of cupped with fingers apart.

 

When every piece of ice settled, Hydro-man was gone, and Tony let out the breath of relief. He rolled on his back, and let out the bitter laugh. “Holy shit… I've never done anything… This big.”

Steve smiled, leaned in, wiped at the blood and kissed his cheek. “You did great, love.”

“Mr. Stark, that was SO cool!” a loud voice ranged through comms… Or not?

No, Peter was climbing the reef with a wide smile plastered on his uncovered face. Tony closed his eyes and frowned his eyebrows. “Put your mask on and lower your voice, or tomorrow there will be the photos of your face and my fin with the headline 'The true nature of Avengers revealed! Spiderman's baby fish and Tony Stark is the mama fish!' all over the news.”

 

Peter cringed and pulled the mask back on. “We should hurry and put you back into the suit, Mr. Stark. Others would be worried,” he told Tony.

“Right. F.R.I.D.A.Y., fly me over here. Mr. Parker, you're going to play a drown fish for a little while for the cover. Mr. Rogers, what about you take the poor Ms. Maximoff and buy us a little more time?”

They quickly executed Tony's plan, which included another magic - Tony raised a hand over his tail and slowly started to grip his fist. All of the water drops evaporated from his body with a loud hiss, and then he turned back into the human, stepped into the suit and took Peter into the arms.

Of course, the others had questions. But Tony pretended to have no answers, and so did Steve. No one questioned Peter, thanks to his form being curled up in Iron Man's arms and occasionally letting out a pained cough. The kid really had a great dramatic talent.

“I just saw what was happening, waited for a while, and then blew the fucker's head off. What's so weird about that? Let's go home, it's coffee time.”

 

So, Steve now dated a merman. Interesting discovery. And really delightful one. There was surely more to this fact, and he still had a million questions for Tony, but one thing was for sure - he would be there for Tony for every other step of the way he chooses to take.

 

**Author's Note:**

> Let me how any thoughts you have <3 I would always be extremely grateful for any kudos and comments. Also, if you have any suggestions or prompts as what would you like to see in the series, let me know here in comments or in my [tumblr](http://childofhebe.tumblr.com/).


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